Ignition, as well as the subsequent spread of smoke in the room, leads not only to large financial losses, but also to the death of people. Most of us believe that in a fire, the main danger comes from exposure to high temperatures, but sad statistics prove that exposure to harmful substances and combustion products is no less dangerous to health.
Operating principle
The natural smoke exhaust system is based on the principle of air heat flow. It has several ways to control the mechanisms: remote control of smoke removal hatches using infrared rays, control panels and special sensors, as well as manual buttons.
Natural motivation ventilation systems can be used in all types of rooms, you just need to select the necessary scheme. SNiP (sanitary norms and rules) determine all the necessary indicators of fire resistance for each type of room.
Depending on the purpose of the enterprise and its cross-country ability, various combinations of the system can be installed: separate windows with electronic control for enterprises with small crowds or special complex systems that satisfy more serious fire safety requirements .
Design and calculation of smoke removal hatches
Design of smoke removal systems is carried out in several stages.
First of all, it is necessary to study all the technical documentation for the installation object.
The next stage involves the inspection of existing ventilation shafts (if any) and their detailed analysis. And only after that you can proceed directly to the calculations.
Inspection of the design object is a very important stage, since only after it you can choose the most suitable equipment for this room. In the absence of ventilation shafts at the facility, experts determine whether there is the possibility of additional communications. If this is possible, you can start the calculation.
Smoke Hatch Functions
Hatches are designed so that they can be used to:
- Natural, uniform lighting. As you know, overhead lighting is twice as effective as lateral. Since smoke hatches illuminate almost every square meter of a room, the savings in lighting costs are significant. In addition, natural daylight increases working efficiency and improves well-being, which is very important in office rooms.
- Natural ventilation. The constant circulation of fresh air ensures the maintenance of a comfortable temperature in the room, which again allows you to significantly save the cost of artificial ventilation.
- Smoke removal. Emergency smoke evacuation ensures the efficient use of evacuation routes and the efficient operation of rescue services.
- Significant simplification of engineering systems. Smoke exhaust hatches in certain cases can eliminate the need for artificial air vents.
Manhole Control Systems
Smoke extraction hatches are controlled by three specialized types of systems: ventilation control system, smoke control system and mixed system.
Also, systems are divided according to the type of control mechanism. They can be of three types: pneumatic, electric and pneumatic-electric.
Smoke extraction hatches activate the control system automatically with the help of special sensors that respond to an increase in air temperature or smoke in the room. However, at the request of the client, the smoke exhaust system can be additionally equipped with remote and manual triggers, as well as triggering through a fire alarm system.
In addition, the ventilation hatches control system can be equipped with special sensors and a weather station. In this case, with strong winds and precipitation, smoke exhaust hatches will close automatically.
Practical recommendations for installing smoke exhaust hatches
The main condition under which the installation of smoke removal hatches can be considered correct is their uniform location on the roof of the building. However, if materials of different burning intensities are located in the room, uneven placement of hatches is allowed.
When installing hatches, the angle of the roof should be taken into account : if it is less than 12 degrees, then the maximum distance from the edge of the roof to the hatches is 10 meters, if it is more than 12 meters, the distance increases to 20 meters.
The distance between the hatches must be at least 20 meters and at least the sum of the long sides of the two hatches (or their diagonals).
From a practical point of view, a large number of small hatches will cope much more effectively with their task than a small number of large ones. A roof slope of less than 12 degrees implies the mandatory installation of at least one hatch per 200 square meters. m, more than 12 degrees - 400 square meters. m
Smoke exhaust hatches can be installed on roofs with different types of coatings: membrane, reinforced concrete, etc. It is imperative to take into account the layout and load calculated at the design stage. The most common consequence of errors at this stage is room overcooling in winter and overheating in the hot season.
Special requirements
When determining the number of smoke removal hatches in crowded places, their area should equal or be more than 3% of the floor area of this room.
The methodology for calculating the area of the smoke exhaust hatches of the theater is as follows: if the floor area of the stage is less than 150 square meters. m, then smoke removal hatches should be at least 3% of it. If the surface area of the scene exceeds 150 square meters. m, then the area of smoke removal hatches is calculated by the formula: A = 0.5 √ 2F-100 (F is the surface area of the stage floor).
Thus, the article discusses in detail the types of smoke removal hatches and issues of their installation.